Composite laminated catheter with flexible segment and method of making same

ABSTRACT

A medical catheter including a composite laminated shaft having a segment that is mechanically deformed to have reduced stiffness.

FIELD OF THE INVENTION

The present disclosure relates generally to a medical catheter havingvariable flexibility along its length, and more particularly, to acomposite laminated catheter with a mechanically deformed segment havingreduced stiffness.

BACKGROUND OF THE INVENTION

A stenosis, or narrowing of a blood vessel such as an artery maycomprise a hard, calcified substance and/or a softer thrombus (clot)material. There have been numerous therapeutic procedures developed forthe treatment of stenosis in an artery. One of the better-knownprocedures is percutaneous transluminal coronary angioplasty (PTCA).According to this procedure, the narrowing in the coronary artery can bereduced by positioning a dilatation balloon across the stenosis andinflating the balloon to re-establish acceptable blood flow through theartery. Additional therapeutic procedures may include stent deployment,atherectomy, and thrombectomy, which are well known and have proveneffective in the treatment of such stenotic lesions. Distal occlusion orfiltration, with or without aspiration embolectomy, have also beendeveloped as adjunctive procedures to prevent downstream embolization bycollecting and removing atheroembolic debris that may be generatedduring any of the above therapies. Increasingly specialized aspirationcatheters have been developed for aspiration of body fluids contaminatedwith thrombus or embolic debris before, during and/or after an arterialintervention.

The therapeutic procedure typically starts with the introduction of aguiding catheter into the cardiovascular system from a convenientvascular access location, such as through the femoral artery in thegroin area or other locations in the arm or neck. The guiding catheteris advanced through the arteries until its distal end is subselectivelylocated in a branch vessel leading to the stenosis that is targeted fortreatment. During PTCA, for example, the distal end of the guidingcatheter is typically inserted only into the origin of a native orbypass graft coronary artery. A guidewire is advanced through a centralbore in the guiding catheter and positioned across the stenosis. Aninterventional therapy device, such as a balloon dilatation catheter, isthen slid over the guidewire until the dilatation balloon is properlypositioned across the stenosis. The balloon is inflated to dilate theartery. To help prevent the artery from re-closing, a physician canimplant a stent inside the artery. The stent is usually delivered to theartery in a compressed shape on a stent delivery catheter and expandedby a balloon for implantation against the dilated arterial wall. Priorto the insertion and use of the interventional therapy catheter, anaspiration catheter may be advanced over the guidewire and used tosuction thrombus that may be clinging to the stenosis. An aspirationcatheter can also be used following the therapy catheter to removecontaminated blood that has been held close to the treatment area bytemporary occlusion or filtration devices.

In order for the physician to direct the guiding catheter and/oraspiration catheter to the correct location in the vessel, the physicianmust apply longitudinal forces, and sometimes apply rotational forces.For the catheter to transmit these forces from the proximal end to thedistal end, the catheter must be rigid enough to be pushed through theblood vessel, a property sometimes called pushability, but yet flexibleenough to navigate the bends in the blood vessel. The catheter may alsorequire sufficient torsional stiffness to transmit the applied torque, aproperty sometimes called torqueability. To accomplish this balancebetween longitudinal rigidity, torsional stiffness, and flexibility,there is often a support member added to the catheter shaft. Thissupport member is often comprised of a woven reinforcement or coiledfilament embedded in the shaft. This support wire is often embeddedbetween two adherent layers of tubing to form a composite laminatedcatheter shaft.

Using the femoral artery approach in a PTCA procedure, a catheter ispassed upward through the aorta, over the aortic arch, and down to thecoronary artery to be treated. It is preferable the guiding catheter oraspiration catheter have a soft tip or flexible section foratraumatically passing through the selected vessels. Therefore, it isadvantageous to have the proximal section be rigid to transmit theapplied forces, but to have a distal section be more flexible to allowfor better placement of the catheter distal section within tortuousvasculature. The need for this combination of performance features makesit desirable for a catheter shaft to have variable flexibility along thelength of the catheter. More specifically, it is desirable for acatheter to have increased flexibility near the distal end of thecatheter shaft and greater stiffness near the proximal end.

One approach used to balance the need for pushability and torqueabilitywhile maintaining adequate flexibility has been to manufacture acatheter that has two or more discrete tubular portions over its length,each having different performance characteristics. For example, arelatively flexible distal section may be connected to a relativelyrigid proximal section. When a catheter is formed from two or morediscrete tubular members, it is often necessary to form a bond betweenthe distal end of one tubular member and the proximal end of anothertubular member. This method requires substantial manufacturing steps toassemble the various sections and makes it difficult to manufacture theentire catheter shaft utilizing low-cost coextrusion technology.Further, such a shaft design may include relatively abrupt changes inflexibility at locations where material changes occur.

Various other approaches for achieving variable stiffness of thecatheter shaft include varying the braid pitch of the reinforcementlayer and/or varying the properties of materials used in construction,such as by removing a selected distal portion of an outer tubular layerof the catheter shaft and replacing that distal portion with one or moresections of more flexible tubing. A unitary catheter shaft arrangementwith variable stiffness is also known that incorporates one or morelayers of a material that is curable by ultraviolet light, whereinselected portions of the catheter shaft are subjected to radiation tocure the material and thereby increase the stiffness of the shaft in thetreated area. Another catheter having variable stiffness is taught inU.S. Patent Application Publication No. US 2004/0225278 A1 to Poole, etal. The Poole, et al. publication teaches a catheter having varyingstiffness achieved by making lamination bonds of varying integritybetween a liner and an outer shell.

However, a need still exists for guiding catheter shafts that can beeasily manufactured, such as by continuous extrusion, co-extrusionand/or other reel-to-reel processes, and have a variable stiffnesswithout assembling multiple components of the shaft or attending todifficulties inherent in irradiated variable-stiffness catheters, suchas the limitations in the choice of catheter materials and in thecontrol of the final catheter properties.

SUMMARY OF THE INVENTION

An embodiment of the present disclosure is a catheter for placement in apatient's vessels, such as the vasculature. The catheter includes acomposite laminated catheter shaft comprising an elongate flexibleliner, an elongate flexible jacket surrounding the liner, and areinforcement layer interposed between the liner and the jacket. Asegment of the shaft is mechanically deformed to have reduced stiffness.The disclosure is applicable to various kinds of composite laminatedcatheters, including guiding catheters having a curvilinear portion andaspiration catheters having a dual lumen portion.

Another embodiment of the present disclosure is a method of making acomposite laminated catheter shaft comprising an elongate flexible linerhaving, an elongate flexible jacket surrounding the liner, and areinforcement layer interposed between the liner and the jacket. Asegment of the shaft is mechanically deformed to have reduced stiffness.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of this disclosure, as well as the disclosure itself,both as to its structure and its operation, will be best understood fromthe accompanying drawings, taken in conjunction with the accompanyingdescription, in which similar reference characters refer to similarparts, and in which:

FIG. 1 illustrates a guiding catheter according to an embodiment of thepresent disclosure shown positioned within a patient's vascular system;

FIG. 2 illustrates a side view of the guiding catheter of FIG. 1;

FIG. 3 illustrates a side view of an aspiration catheter according to anembodiment of the present disclosure;

FIG. 4 is a transverse cross-sectional view of the catheters of FIGS. 2and 3 taken along lines 4-4;

FIG. 5 is a transverse cross-sectional view of the aspiration catheterof FIG. 3 taken along line 5-5;

FIGS. 6 and 7 are partial longitudinal section views of the catheters ofFIGS. 2-4 taken along lines 6,7-6,7 in FIG. 4;

FIG. 8. illustrates a cutaway view of a catheter according to anembodiment of the present disclosure, shown inserted into a schematicdepiction of a deforming apparatus;

FIG. 9 schematically illustrates a process for making a catheteraccording to an embodiment of the present disclosure;

FIG. 10 illustrates an apparatus for rolling a catheter according to anembodiment of the present disclosure;

FIG. 11 illustrates an apparatus for roller swaging a catheter accordingto an embodiment of the present disclosure; and

FIG. 12 illustrates a side assembly view of a portion of a cathetershaft according to an embodiment of the present disclosure showing agroove, a fill section and a sleeve.

DETAILED DESCRIPTION OF THE INVENTION

Specific embodiments of the present disclosure are now described withreference to the figures, wherein like reference numbers indicateidentical or functionally similar elements. The terms “distal” and“proximal” are used in the following description with respect to aposition or direction relative to the treating clinician. “Distal” or“distally” are a position distant from or in a direction away from theclinician. “Proximal” and “proximally” are a position near or in adirection toward the clinician.

The following detailed description is merely exemplary in nature and isnot intended to limit the disclosure or the application and uses of thedisclosure. Although the description of the disclosure is in the contextof guiding catheters and aspiration catheters for treatment of coronaryarteries, the disclosure is not so limited, and the disclosure may beuseful for other types of catheters and for treatment of other bloodvessels such as carotid, renal or any other peripheral, viz.non-coronary arteries. A catheter embodying one or more features of thedisclosure may or may not have a lumen or bore there through, and thecatheter may also carry therapeutic or sensing elements, e.g., balloons,electrodes or stents, and may be used in other body passageways where itis deemed useful. Furthermore, there is no intention to be bound by anyexpressed or implied theory presented in the preceding technical field,background, brief summary or the following detailed description.

FIG. 1 illustrates guiding catheter 100 for use with a therapeuticdevice (not shown) positioned within a patient's vascular system 150. Ina representative use of the catheter, the clinician inserts a distal endof guiding catheter 100 through introducer sheath 160 into vascularsystem 150, typically through a femoral artery in the groin area.Guiding catheter 100 is then advanced through aorta 165 until the distalend of the catheter is located in the ostium of a targeted branch artery170. In the example shown, branch artery 170 is a patient's leftcoronary artery, and the distal end of guiding catheter 100 ispositioned proximal of a stenosis 175. Once positioned, a therapeuticdevice, such as a balloon dilatation catheter including a dilatationballoon, may be advanced through guiding catheter 100 to providetreatment of stenosis 175. Upon completion of the interventionalprocedure and removal of any therapeutic device, guiding catheter 100 iswithdrawn from the patient's vascular system 150.

FIG. 2 illustrates a side view of an embodiment of guiding catheter 100,including an elongate shaft 204 with a distal end 206 having an optionalsoft tip. As shown in FIG. 4, a bore or lumen 210 extends through shaft204 between an open proximal end 208 and distal end 206. In anembodiment of the present disclosure, bore 210 has a low-frictionsurface and is sized and shaped to receive and direct there through avariety of treatment devices, such as guidewires and/or therapeuticdevices including, but not limited to balloon catheters, stent deliverysystems, or aspiration catheters. In another embodiment, bore surface240 may provide a slippery interior surface for reducing frictionalforces between the interior surface of guiding catheter 100 and devicesthat may be moved through bore 210.

A connector fitting 102 is coupled to, and provides a functional accessport at proximal end 208 of guiding catheter 100. Fitting 102 isattached to catheter shaft 204 and has a central opening incommunication with open proximal end 208 and bore 210 to allow passageof various fluids and/or therapeutic devices there through. Connectorfitting 102 may be made of metal or of a hard polymer, e.g. medicalgrade polycarbonate, polyvinyl chloride, acrylic, acrylonitrilebutadiene styrene (ABS), or polyamide, that possesses the requisitestructural integrity, as is well known to those of ordinary skill in theart.

Catheter shaft 204 is a single lumen tubular structure that is designedto advance through a patient's vasculature to remote arterial locationswithout buckling or undesirable bending. In an embodiment of the presentdisclosure, catheter shaft 204 also has reduced stiffness within atleast flexible segment 114. Catheter shaft 204 may include a pre-formedcurvilinear shape in a distal portion for providing backup support astherapeutic catheters are advanced through bore 210 of guiding catheter100 and across stenosis 175. As shown in FIG. 2, any one of a number ofpre-formed curvilinear shapes may be incorporated into guiding catheter100, such as Judkins-type or Amplatz-type curves, as non-limitingexamples.

FIG. 3 illustrates a side view of an embodiment of an aspirationcatheter 300, which has several inventive features in common withguiding catheter 100. Aspiration catheter 300 includes an elongate shaft304 with a distal end 206 having an optional soft tip. As shown in FIG.4, bore 210 extends through shaft 304 between open proximal end 208 anddistal end 206. Connector fitting 102 is coupled to, and provides afunctional access port at proximal end 208 of aspiration catheter 300.Fitting 102 is attached to catheter shaft 304 and has a central openingin communication with open proximal end 208 and bore 210 to allowpassage of various body fluids there through. In an embodiment of thepresent disclosure, catheter shaft 304 also has reduced stiffness withinat least flexible segment 314.

Single operator aspiration catheter 300 includes a dual lumen portion316 that is substantially shorter than the full length of catheter 300.In the embodiment shown in FIG. 3, dual lumen portion 316 is shorterthan flexible segment 314 and comprises a distal portion of segment 314.Other arrangements are also possible, including, but not limited to duallumen portion 316 comprising a middle portion, a proximal portion, orall of flexible segment 314. Dual lumen portion 316 extends proximallyfrom distal fluid port 307 disposed at or adjacent the distal end oftubular body 304 to open proximal end 309 of guidewire lumen 511. Asshown in transverse cross-section at FIG. 5, dual lumen portion 316comprises guidewire tube 550 extending alongside flexible segment 314 ofcatheter shaft 304 to arrange aspiration lumen 210 and guidewire lumen511 in a parallel or side-by-side configuration. At least within duallumen portion 316, jacket 230 is absent from catheter shaft 304; jacket230 having been selectively removed from at least a portion of shaft304. Within dual lumen portion 316, over sleeve 355 surrounds andsecures together guidewire tube 550 and flexible segment 314 of shaft304. A process for selectively removing a portion of jacket 230, and forpositioning and attaching guidewire tube 550 and over sleeve 355 to makedual lumen portion 316 will be discussed further below with regard toFIG. 12.

FIG. 4 illustrates a transverse cross-section of composite laminatedcatheters 100 and 300, as the cross-sections would appear in shafts 204,304 and in flexible segments 114, 314. As shown in FIG. 4, cathetershafts 204, 304 include a liner 215, a reinforcement layer 220, and ajacket 230. Liner 215 is tubular and defines bore 210, which is sizedand shaped as described above. In a guiding catheter embodiment of thepresent disclosure, those of ordinary skill in the art may appreciatethat any one of numerous low-friction, biocompatible materials such as,for example, fluoropolymers (e.g. PTFE, FEP), polyolefins (e.g.polypropylene, high-density polyethylene), or high density polyamides,may be used to make liner 215 or to make a coating on surface 240 ofbore 210 to provide good flexibility and good movement of catheter 100over a guidewire and/or good movement of a therapeutic device withinguiding catheter 100. In an embodiment such as aspiration catheter 300,where low friction is not required for aspirating fluids through bore210, liner 215 may comprise alternative materials such as a relativelylower-density polyamide or a polyethylene block amide copolymer (PEBA).In the present embodiment of aspiration catheter 300, liner 215comprises PEBA 70D, viz. having a hardness or durometer of 70 the shoreD scale.

Reinforcement layer 220 enhances the torsional strength and inhibitskinking of catheter shaft 204, 304 during advancement of catheters 100,300 within the patient's vasculature. Reinforcement layer 220 ispositioned between and is substantially coaxial with liner 215 andjacket 230. In various embodiments, reinforcement layer 220 may beformed by braiding multiple filaments or winding at least one filamentover liner 215 or by applying a metal mesh over inner layer 215. Braidedor wound filaments may comprise high-modulus thermoplastic or thermo-setplastic materials, e.g., liquid crystal polymer (LCP), polyester, oraramid polymer e.g. poly-paraphenylene terephthalamide (Kevlar® fromE.I. du Pont de Nemours and Company, Wilmington, Del., U.S.A.).Alternatively, braided or wound filaments may comprise metal wires ofstainless steel, superelastic alloys such as nitinol (TiNi), refractorymetals such as tantalum, or a work-hardenable super alloy comprisingnickel, cobalt, chromium and molybdenum. The reinforcing filaments mayhave cross sections that are round or rectangular, i.e. flat or ribbonshapes.

Examples of woven or braided reinforcement layer 220 may includeone-over-one plain weave patterns or two-over-two basket weave patterns,and may typically range in pitch, or pic count from 30 to 70 pics perinch. Braided reinforcement layer 220 may include a plurality offilaments having the same material and cross sectional shape, or layer220 may have a combination of filaments that differ from one another inat least one aspect. In the current embodiment of aspiration catheter300, reinforcement layer 220 comprises a hybrid basket weave of twodifferently-dimensioned flat wires, both wires being made of 304Vstainless steel. Reinforcement layer 220 may include interstices formedwithin a mesh or formed between filaments that are applied around liner215.

Jacket 230 provides support to catheter shafts 204, 304 and coverage ofreinforcement layer 220. Jacket 230 is coaxial with liner 215 andreinforcement layer 220, and may be a single or unitary tube thatcontinuously extends from proximal end 208 to distal end 206 of cathetershafts 204, 304. In an embodiment of the present disclosure, jacket 230is manufactured of a polyamide, such as a polyether block amidecopolymer or nylon 6,6. Jacket 230 may be thermoplastically extrudedover, and forced into any interstices in, reinforcement layer 220 topromote adhesion between the jacket material and liner 215 and toencapsulate reinforcement layer 220.

FIG. 6 shows a longitudinal semi-cross-sectional view of an embodimentof the composite laminated wall structure of catheter shafts 204, 304.Jacket 230 is shown extending through interstices between braidfilaments 625 to adhere to liner 215 and encapsulate reinforcement layer220. FIG. 7 illustrates, also in longitudinal semi-cross-section,mechanically deformed segments 114, 314 that have increased flexibility,viz. reduced bending stiffness, as compared to undeformed segments ofcatheter shafts 204, 304, shown in FIG. 6. Segments 114, 314 may bedeformed using a radial or diametric compression process such asrolling, swaging, rotary swaging, roller swaging, hydraulic swaging, andradial forging, which processes will be described in further detailbelow. Besides the radial or diametric compression stresses applied bythe processes discussed herein, it will be understood that any othertype of mechanical stress, such as tension, torsion or bending can beapplied to catheter shafts 204, 304 to result in reduced bendingstiffness. The selected mechanical deformation process subjects the wallin shaft segmentsl 14, 314 to one-time or repeated cyclic stressessufficient to create one or more physical changes in the compositelaminated wall structure; the physical changes reducing the bendingstiffness of the catheter shaft. The action or resulting effects ofmechanical deformation of the catheter material may be described as worksoftening, a demonstrable phenomenon known in fields of metallurgy andgeology as being opposite to work hardening.

One of the physical changes that may result from the mechanicaldeformation of catheter shaft segments 114, 314 is the formation of oneor more regions 760 of delamination in the composite laminated wallstructure. As shown in FIG. 7, delamination regions 760 may occurbetween jacket 230 and liner 215, e.g. in the interstices ofreinforcement layer 220. One or more delamination regions 760 may alsobe created adjacent filaments 625 to at least partially loosen thepreviously formed encapsulation of reinforcement layer 220 by thesurrounding materials of jacket 230 and/or liner 215. Prior tomechanical deformation of segments 114, 314, delamination regions 760are securely laminated within shafts 204, 304, as discussed above. Thus,the deformation process may be considered as intentionally imparting acontrolled or limited degree of damage to selected segments 114, 314 ofthe laminated structure of catheter shafts 204, 304. Delaminationregions 760, singly or in combination act as loose cells to reduce thebending stiffness of shafts 204, 304 by allowing the adjacent shaftelements to slide or move relative to each other during bending of shaftsegments 114, 314. A plurality of delamination regions 760 may bedistributed somewhat randomly within the wall of shaft segments 114,314, or regions 760 may be distributed in a substantially uniformpattern to provide a substantially consistent reduction in stiffnessalong segments 114, 314.

Another physical change that may result from the mechanical deformationof catheter shaft segments 114, 314 is the permanent reduction in wallthickness T1 of shafts 204, 304 to wall thickness T2 of segments 114,314, as shown in FIGS. 6 and 7. Because the catheter shaft materials aregenerally not compactable, mechanical deformation may thin the catheterwalls by displacing material(s) longitudinally. Such an increase inlength of deformed segments 114, 314 can be planned-for in the design ofcatheters 100, 300, or any excess length can be trimmed as desired.Because the materials of filaments 625 are usually particularlyincompressible, reduced wall thickness T2 may typically be accomplishedby thinning jacket 230 and/or liner 215.

In an embodiment of the disclosure, another physical change that mayresult from the mechanical deformation of catheter shaft segments 114,314 is a permanent reduction in the pitch of reinforcement layer 220. Inbraided or spirally wound reinforcement layers, measurement units ofpitch typically reflect the number of filament turns or “pics” per unitlength, e.g. pics per inch. In embodiments where mechanical deformationpermanently thins the catheter walls by displacing materialslongitudinally, reinforcement filaments 625 are axially separated tolongitudinally expand the interstices, thus reducing the pitch inreinforcement layer 220. Changing the pitch of braided catheter shaftsis known by those skilled in the art to affect the stiffness of acatheter shaft. Although reducing braid pitch typically increases thebending stiffness of a reinforced catheter shaft, in accordance with thedisclosure, this affect is more than counterbalanced by other physicalchanges that may occur in deformed segments 114, 314 to achieve anoverall reduction in segment stiffness.

Yet another physical change that may result from the mechanicaldeformation of catheter shaft segments 114, 314 is the permanentreduction in diameter D1 of shafts 204, 304 to diameter D2 of segments114, 314, as shown in FIGS. 6 and 7. FIGS. 2 and 3 also illustrate, withexaggeration for clarity, segments 114, 314 being stepped-down indiameter relative to shafts 204, 304. However, it should be understoodthat segments 114, 314 may have little or no permanent reduction indiameter following deformation; segments 114, 314 relying instead onother physical changes therein to provide the desired reduction instiffness. In embodiments where it is desirable to maintain the diameterof bore 210 substantially uniform throughout the catheter, reduceddiameter D2 is achieved substantially by permanently reducing wallthickness from T1 to T2, as described above. The diameter of bore 210can be maintained during the deformation process by supporting bore 210with an incompressible mandrel, as will be described below.

Table 1 shows a measured reduction in stiffness resulting frommechanical deformation on one set of sample shaft segments. The sampleswere mechanically deformed in a rotary swager using a die set having adiameter of 1.23 mm (0.049 in). In these samples, bore 210 was uniformlymaintained with a mandrel having a diameter of 1.04 mm (0.041 in). Theaverage bending stiffness was reduced by 28% with a permanent diameterreduction of 4%. The braid pitch was permanently reduced by 10%, whichwould typically increase the stiffness of a reinforced catheter shaft,as described above. Thus, the potentially undesirable increase change inbraid stiffness was more than offset by one or more other physicalchanges brought about by mechanical deformation of the samples.

TABLE 1 Outside Diameter Braid Pics/inch Stiffness Not Deformed 1.37 mm(0.054 in) 86.5 63.5 Deformed 1.32 mm (0.052 in) 77.5 45.5

An embodiment of the present disclosure includes a method ofmanufacturing catheter shafts 204, 304 having segments that areselectively made more flexible by a mechanical deformation or worksoftening process. In one embodiment, as shown in FIG. 8, andschematically illustrated in step 970 of the flow chart depicted in FIG.9, elongate reinforced composite tubing to be used for catheter shafts204, 304 is formed in a first step of extruding a thermoplasticmaterial, such as 70D PEBA, optionally over a mandrel 801, to formtubular liner 215. Mandrel 801 may comprise an elongate wire or plasticcore, and defines the final diameter of bore 210. Using a melt-extrusionprocess in step 970, many lengths of liner 215 may be continuouslyformed, and wound on a reel for storage, if desired. In step 975, flatstainless steel wires 625 are selected and braided over liner 215 toform reinforcement layer 220, passing the long subassembly from reel toreel. In step 980, a jacket material, such as a polyamide, isthermoplastically extruded over reinforcement layer 220 to form jacket230, again passing the long subassembly from reel to reel. Jacket 230may extend through the interstices of braided reinforcement layer 220 toform a bond with liner 215, as shown in FIGS. 6 and 7. Alternatively, anadhesive or other type of tie layer material may be incorporated to bondtogether liner 215, reinforcement layer 220, and jacket 230, as would bewell known to those of skill in the art.

The elongate composite laminated tubing subassembly is then drawn from areel and is cut in appropriate lengths to form a number of cathetershafts 204, 304. Shaft 204 may, e.g. be approximately 100 cm long foruse in guiding catheter 100. Shaft 304 may, e.g. be approximately 140 cmlong for use in aspiration catheter 300. In accordance with alternativemethods, catheter shafts 204, 304 may be fabricated one at a timeinstead of using continuous or reel-to-reel processes. Suchone-at-a-time catheter manufacturing is less efficient than reel-to-reelprocessing, but this process may be useful if one or more selectedplastic materials, e.g., PTFE, require paste extrusion, which cannotproduce very long extrudates. If mandrel 801 was used duringmanufacturing, then it is removed from catheter shafts 204, 304 toprovide open bore 210.

In step 990, segments 114, 314 of catheter shafts 204, 304 aremechanically deformed in a deforming apparatus 890. FIG. 10 illustratesa first example, in which deforming apparatus 890 comprises a pair ofplatens 1090A, 1090B for rolling shafts 204, 304 laterally there betweenunder diametrical pressure F to mechanically deform segments 114, 314.Platens 1090A, 1090B may be reciprocated relative to each other untilthe desired physical changes have been effected in segments 114, 314.Alternatively, deforming apparatus 890 may comprise a pair of opposed,non-reciprocating jaws similar to platens 1090A, 1090B, the jaws beingusable for hydraulically swaging or forging shafts 204, 304 laterallythere between under diametrical pressure to mechanically deform segments114, 314.

FIG. 11 illustrates an example of a roller swaging process, whereindeforming apparatus 890 comprises a pair of pinch rollers 1190A, 1190Bfor rolling shafts 204, 304 axially there between under diametricalpressure F to mechanically deform segments 114, 314. Rollers 1190A,1190B may be circumferentially grooved (not shown) for distributingmechanical deformation forces more uniformly about the circumferences ofshafts 204, 304.

Deforming apparatus 890 may also comprise alternative swaging mechanismssuch as a rotary swager (not shown). As is well-know to those of skillin the art, a rotary swager comprises a plurality of dies slidablydisposed within radial slots in a rotatable spindle. The spindle rotateswithin a series of circumferentially arranged rollers that drive thedies toward the center of the spindle. Tangential inertia, thefictitious “centrifugal force,” tends to keep the dies away from thecenter of rotation when they are momentarily disposed between rollers.The dies cyclically close over shafts 204, 304 to deform the materialinto segments 114, 314. Shafts 204, 304 can be plunged, viz. insertedand withdrawn from the center of the dies of the rotary swager. Rotaryswagers may also be provided with an engagement/disengagement featurewhereby the interaction of the dies and the rollers can be selectivelyoperated while the spindle rotates. Such a feature may allow shafts 204,304 to be axially moved in a rotary swager, without deformation, to andfrom a location where swaging is desired. In this way, swaging may beperformed at selected locations of shafts 204, 304 besides at the ends.

Mandrel 801 may be left in place during a mechanical deformation step tosupport bore 210. Alternatively, mandrel 801 may be removed and replacedwith a different, e.g., harder mandrel. For example, elongate mandrel801 may comprise an extrudable thermoplastic, e.g., acetal resin, forthe reel-to-reel steps of manufacturing. Then, the acetal mandrel 801may be replaced with a metal, e.g., stainless steel mandrel for thedeformation step. Using a rigid support mandrel may also permitone-sided deformation of catheter shafts 204, 304, viz. applying radial,rather than diametrical compression. Next, the remaining components,e.g., a soft tip and/or fitting 102 are secured to catheters 100, 300.In guiding catheter 100, a desired curvilinear shape is heat-set into adistal portion of shaft 104.

As illustrated in FIG. 12, catheter shafts 204, 304 can optionallyinclude an annular shaped, circumferentially extending groove 1216,which may be cut out of catheter shafts 204, 304 as described in U.S.Pat. No. 6,375,774, which is incorporated herein by reference in itsentirety. Groove 1216 may provide one or more additional portions ofvarying stiffness in catheter shafts 204, 304 or in deformed segments114, 314. Further, groove 1216 may provide a transition region betweenrelatively stiffer and relatively more flexible portions of cathetershafts 204, 304 or deformed segments 114, 314. This transition regionmay prevent or reduce kinking and/or collapsing of catheters 100, 300and may provide improved tracking and movement in a patient's vessel.

Fill section 1235 may comprise one or more fill components 1252, 1254having hardness(es) different from the hardness of jacket 230; fillsection 1235 being positionable in groove 1216 to provide variableflexibility to catheter shafts 204, 304 or deformed segments 114, 314.Alternatively, fill section 1235 may comprise guidewire tube 550 andover sleeve 355 to make dual lumen portion 316 of shaft 304, asdiscussed above regarding FIGS. 3 and 5. In an embodiment of cathetershaft 204, groove 1216 may be located adjacent the shaft distal end ofand have a groove length 1246, e.g., of approximately three centimeters.In this embodiment, the groove depth may be approximately equal to thethickness of outer jacket 230. Fill components 1252, 1254 may includethermoplastic materials similar to the materials discussed aboveregarding jacket 230, such as amides or blends thereof, and can bemanufactured, e.g., by extrusion. In an embodiment of catheter shaft304, groove 1216 may have a groove length 1246, e.g., of approximately 9centimeters. FIG. 12 also illustrates a tubular sleeve 1258 which can beused to attach guidewire tube 550 and over sleeve 355 to shaft 304, orto attach fill components 1252, 1254 to catheter shaft 204. Sleeve 1258may be a piece of shrink tubing which is heated above the glasstransition temperatures of over sleeve 355 or the fill components 1252,1254, whereupon sleeve 1258 shrinks and compresses heat-softenedelements such as over sleeve 355 or fill components 1252, 1254 intogroove 1216, according to methods disclosed in the '774 patent.

Groove 1216 may be formed in a portion of jacket 230 with a removingdevice 1244, which may be, e.g., a grinding wheel, an abrasive brush, oran excimer laser. The excimer laser may remove a selected portion ofjacket 230 without damaging reinforcement section 220. Further, theexcimer laser may remove material in the interstices of reinforcementsection 220, allowing for a stronger bond between the fill section 1235,reinforcement section 220 and liner 215. Groove 1216 may be formed andfilled with fill section 1235 before or after segment 114 ismechanically deformed in catheter shaft 204.

While the particular medical catheters 100, 300 as herein shown anddisclosed in detail are fully capable of obtaining the objects andproviding the advantages herein before stated, it is to be understoodthat they are merely illustrative of the presently preferred embodimentsof the disclosure and that no limitations are intended to the details ofconstruction or design herein shown other than as described in theappended claims.

1. A medical catheter comprising: an elongate catheter shaft comprising:a flexible polymeric liner; a flexible polymer jacket adherentlysurrounding the liner; a reinforcement layer interposed between theliner and the jacket; and at least one segment of the shaft havinginternal radial compressive structural deformations characterized by areduction in longitudinal bending stiffness of the segment; and afitting mounted at a proximal end of the shaft.
 2. The medical catheterof claim 1 wherein the catheter shaft further comprises a wall, thewall, in the region of the deformations being thinner than the wall of ashaft segment without such structural deformations.
 3. The medicalcatheter of claim 2 wherein the catheter shaft further comprises asubstantially uniform diameter bore extending therethrough.
 4. Themedical catheter of claim 1, wherein the reinforcement layer comprisesone or more filaments braided or spirally wound about the liner andforming a plurality of interstices, the jacket and the liner beingadhered to each other through the interstices.
 5. The medical catheterof claim 4 wherein the at least one shaft segment has a braid pitch thatis less than a braid pitch of a segment of the shaft without suchstructural deformations.
 6. The medical catheter of claim 1, wherein theinternal radial compressive structural deformations comprise a pluralityof regions of delamination between the liner and the jacket.
 7. Thecatheter of claim 6, wherein the regions of delamination are distributedwithin the wall of the segment having the deformations to provide asubstantially consistent reduced stiffness.
 8. The catheter of claim 1,further comprising a guidewire tube extending alongside a selectedportion of the shaft and being secured thereto, the guidewire tubehaving a round lumen extending longitudinally therethrough and beingopen at proximal and distal ends thereof for slidably receiving amedical guidewire.
 9. The catheter of claim 8, wherein the jacket isabsent along the selected portion of the shaft to expose at least anouter surface of the reinforcement layer, the guidewire tube beingsecured there to.
 10. The catheter of claim 9, wherein the selectedportion of the shaft is disposed distally adjacent the deformed segmentof the shaft.
 11. The catheter of claim 1, wherein the segment havinginternal radial compressive structural deformations is disposed adjacenta distal end of the shaft.
 12. The catheter of claim 1, furthercomprising a soft distal tip attached to a distal end of the shaft. 13.The catheter of claim 1, wherein a distal portion of the catheter has apreformed curvilinear shape.